If you want to generate a 64bit-build for Asset-Importer-Lib by using the Visual Studio project files generated by CMake please follow these instructions:
Make sure that you are using a supported cmake ( 2.8 or higher at the moment )- and Visual-Studio-Version ( on the current master VS2010 is deprecated )
Clone the latest master Asset-Importer-Lib from github
Generate the project files with the command:

cmake -G”Visual Studio 14 Win64"

Open the project and build the whole project and enjoy the 64-bit-version of your famous Asset-Importer-Lib.
This should help you if you a struggeling with this feature. We just learned that just switching to code
generation for 64bit does not work.